In general, materials are very important factors to determine the property and the performance of final products in the electric, electronic and mechanical industrial fields.
Since silicon (Si) used as a representative semiconductor device material is weak at the temperature of 100° C. or above, a semiconductor device may erroneously operate or may be failed frequently, so the semiconductor device requires various cooling apparatuses. As silicon (Si) has the physical limitation, wideband semiconductor materials such as SiC, GaN, AlN, and ZnO have been spotlighted as next-generation semiconductor device materials.
When comparing with GaN, AlN and ZnO, SiC represents the superior thermal stability and superior oxidation-resistance property. In addition, the SiC has the superior thermal conductivity of about 4.6 W/Cm° C., so the SiC can be used for fabricating a large-size substrate having a diameter of about 2 inches or above. In particular, a silicon carbide epi wafer having a high quality, which is heavily doped at a low concentration, can be used in the field of high-power devices.
According to the related art, in order to grow the silicon carbide epi layer on a wafer, the silicon carbide is deposited on the wafer in a chamber and an annealing process and/or a cooling process is performed to provide an epi wafer on which the silicon carbide epi layer has been grown.
That is, according to the related art, a silicon carbide wafer has been introduced into a single or batch-type reaction chamber and a layer has been deposited on the silicon carbide wafer. Then, in general, the wafer has been introduced into an annealing apparatus and/or a cooling apparatus and processes for removing defects on the surface of the wafer have been continuously performed, such that a silicon carbide epi wafer has been manufactured.
However, in the above process, it takes so much time to heat or cool the hot zone through induction heating. That is, the temperature in the chamber must be increased to a predetermined temperature in order to grow the epi layer in the chamber. At this time, there is a need for the step of cooling the chamber again after the chamber is heated to the predetermined temperature and the epi layer is deposited.
However, so much time is needed to heat or cool the hot zone area in the chamber. As one example, since it takes two hours or more to heat or cool the hot zone area, the time for the entire process is increased, so that the problem is caused that the product yield of the wafers is reduced.
Therefore, there is a need to omit the repetitive process for heating or cooling the chamber in growing of the silicon carbide epi layer and to provide a process for continuously fabricating the silicon carbide epi wafer. That is, there is a need to provide a process for fabricating the silicon carbide epi wafer by continuously performing the depositing, annealing and cooling processes.